雙連續結構多孔薄膜之製備、物性分析及其在分離程序之應用

Bi-continuous porous membrane: preparation, characterization, and applications in separation processes

尤思婷(Szu-Ting Yu)

指導教授 ： 鄭廖平

淡江大學/工學院/化學工程與材料工程學系碩士班/碩士(2019年)

https://doi.org/10.6846/TKU.2019.00356

摘要

本研究以乾濕式相轉換法(dry-wet phase inversion method)由PVP(polyvinylpyrrolidone) /γ-丁內酯(gamma-Butyrolactone)/聚醚碸與Tween 20/碳酸丙烯酯(propylene carbonate)/聚乳酸兩系統製備多孔型薄膜，前者依PVP及PES之添加量不同，探討其對薄膜之物性與過濾效能之影響，所製得薄膜呈非對稱結構，表面為皮層，內部為手指狀巨孔，隨著PVP添加量增加，上、下表面孔洞逐漸變大，使純水通量提升，當添加至15 wt%時，結構轉變形成雙連續互穿結構；改變PES添加量時，薄膜表面孔洞尺寸變小，上表面變得緊實，使純水通量逐漸下降，薄膜之孔隙度約為60~81%，上表面的接觸角薄膜的抗張強度皆隨著PVP的添加逐漸下降，這是由於上、下表面孔洞變大所致，然而當固定PVP添加量時，抗張強度會隨著PES添加量增加，呈上升趨勢。PVP在薄膜的殘留量乃由NMR分析得知，結果顯示，殘留量佔膜重0.1~6.4 %而PVP的移除率約為73~99.8 %。在純水通量測試中發現隨著PVP的添加通量呈上升趨勢，當PVP添加至15 wt%時，其通量最高可達約1000 LMH。將薄膜進行BSA過濾時，發現BSA之移除率最高可達96%，過濾通量為51 LMH，利用PEG量測薄膜之截留分子量，發現其截留分子量約為137~454 kDa，此現象與純水通量及孔洞大小相互呼應。
後者依Tween 20之添加量及製膜液冷卻時間的不同，探討其對薄膜之物性與孔洞結構之影響，所製得薄膜之冷卻時間維持在10分鐘時，隨著Tween 20添加量增加，上、下面孔洞逐漸變大，截面結構由倒V趨勢轉為上下均一的孔洞，接著再轉為正V趨勢，最後轉變形成雙連續互穿結構，薄膜之孔隙度約為49~55%，抗張強度會隨著Tween 20添加量增加，呈下降趨勢；再添加5 wt% Tween 20而改變製膜液冷卻時間時，薄膜表面孔洞尺寸無太大變化，當冷卻時間達15分鐘時，胞孔縮小並開始產生相互連通之雙連續互穿結構，薄膜之孔隙度約為53~68 %。

關鍵字

聚醚碸 ； 聚乙烯吡咯烷酮 ； 聚乳酸 ； 多氧乙烯山梨聚糖 ； 多孔型薄膜 ； 濕式相轉換法 ； 超過濾 ； 抗汙 ； 截留分子量

並列摘要

In this research, we used the dry-wet phase inversion method to prepare porous membranes from the polyvinylpyrrolidone (PVP) / γ-butyrolactone (GBL) / polyethersulfone (PES) and the Tween 20 / propylene carbonate / poly(lactic acid) system to prepare porous membrane. According to the amount of added different PVP and PES content, we can be divided into 6 series: P16, P16K5, P16K10, P16K15, P13K10, P20K10. All membranes show the asymmetric structure with a dense surface (skin) and porous cross section composed of finger-liked macrovoids. With the increase of added PVP, the pores on the top and bottom surfaces increase, resulting in an increase of the pure flux. When increase of added 15 wt% PVP, the structure transform into bi-continuous porous. Changing the amount of added PES, the surface pore size of the membrane is found to decrease, resulting in a decrease of the pure flux. The porosity of membrane is about 60-81%, and the contact angle of the top surface gradually decreases with the addition of PVP. The tensile strength decrease with the increase of added amount of PVP, which is attributed to the larger pores of the top and bottom surfaces. However, when the added PVP is fixed, the tensile strength increases with the addition of PES. The amount of PVP resided in the membrane has been determined by NMR analysis. The results show that about 73-99.8 % of the PVP is removed during the membrane formation process and the residual amount only accounts for 0.1~6.4 % of the membrane weight. As to the pure water flux increase with the PVP content, when increase of added 15 wt% PVP, the flux are up to 1000 LMH. The BSA filtration experiments show that the rejection ratio of the membrane are up to 96% and permeation flux of BSA solution are 51 LMH. PEG is used to determine the molecular weight cut-off (MWCO) of the membranes. For PES membranes, the MWCO is about 137-454 kDa, these results are consistent with the pure water flux and the pore size.
The latter is based on the addition of different Tween 20 and different cooling time. All membranes show the asymmetric structure. With the increase of added Tween 20, the pores on the top and bottom surfaces increase, and the structure changes from the inverted V and then turns to the positive V trend and finally transform into bi-continuous porous. The porosity of membrane is about 49-55%, and the tensile strength decrease with the increase of added amount of Tween 20. With the increase of cooling time, the pores on the top and bottom surfaces is not much different. When increase of cooling time on 15 min, the cross section pores shrink and transform into bi-continuous porous. The porosity of membrane is about 53-68 %.

並列關鍵字

Polyethersulfone ； Polyvinylpyrrolidone ； porous membrane ； dry-wet phase inversion method ； ultrafiltration ； antifouling capability ； molecular weight cut-off

參考文獻

第二章

[1] World Resources Institute. Aqueduct Project, 2013. Accessed on December 2013, available at http://www.wri.org/resources/charts-graphs/water-stress-country.

[2] M. A. Shannon, P. W. Bohn, M. Elimelech, J. G. Georgiadis, B. J. Marinas, A. M. Mayes, Science and technology for water purification in the coming decades, Nature, 452, 2008, 301–310.

[3] C. A. Quist-Jensen, F. Macedonio, E. Drioli, Membrane technology for water production in agriculture: Desalination and wastewater reuse, Desalination, 364, 2015, 17-32.

[4] WHO, World Health Organization — Water, Fact Sheet 391[Online]. available at http://www.who.int/mediacentre/factsheets/fs391/en/2014 (Accessed:05-Aug-2014).